Investigation on surface treatments of CFRP and aluminum to improve fracture toughness of adhesively-bonded CFRP-aluminum joints

摘要

In this stuy,the role of surface treatments of CFRP (graphite/epoxy composite and aluminum (7075-T6) on the adhesively-bonded CFRP-aluminum joints has been investigated.The CFRP was surface-treated by Ar~+ ion irradiation in an oxygen environment and the aluminum was surface-treated using a DC plasma.Ar~+ ion irradiation treatment was carried out at Ar~+ ion dose of 10~16 ions/cm~2.Plasma treatment was carried out at a volume ratio of acetylene gas to nitrogen gas of 5:5 and the treatment time was 30 s.The effect of surface treatments on the fracture behavior CFRP-aluminum joints was determined form fracture tests using three different CLS (cracked lap shear) specimens: (1) untreated CFRP/untreated aluminum,(2) ion-irradiated CFRP/untreated aluminum and (3) untreated CFRP/alasma-treated aluminum.Fracture behaviors (fracture load,fracture toughnes,fracture surfaces) of these three different speciments were compared.The results showed that both fracture load and fracture toughness of CFRP-aluminum joints were inthe following order:ion-irradiated CFRP/untreated aluminum specimen>untreated CFRP/plasma-treated aluminum specimen > untreated CFRP/untreated aluminum specimen.SEM examination of fracture surfaces showed that fracture occurred as an interfacial failure for untreated speciments.On the other hand,a cohesive failure in the adhesive was the primary fracture mode for specimens surface-treated by ion irradiation or plasma.